EnergyWise House: Elements of an Energy-Efficient House

Insulation An energy-efficient house has much higher insulation R-values than required by most local building codes. For example, a typical house might have haphazardly installed R-11 fiberglass insulation in the exterior walls and R-19 in the ceiling, and the floors and foundation walls may not be insulated. A similar, but well-designed and constructed house's insulation levels would be in the range of R-20 to R-30 in the walls (including the foundation) and R-50 and R-70 in the ceilings. Carefully applied fiberglass batt or roll, wet-spray cellulose, or foam insulations will fill wall cavities completely. Exclusive EnergyWise House Video Report Bonded Logic Insualtion - Bonded Logic UltraTouch Natural Cotton Fiber Insulation, made of post-industrial cotton and denim fibers, brings fire, fungi, and corrosive resistance to batt insulation that is formaldehyde and resin free, requires no warning labels, and can be installed without protective clothing or gear. The thermal bonding process allows Bonded Logic to offer finished products in a wide range of thicknesses and densities to ensure superior soundproofing, maximum thermal performance, and fire resistant insulation free of noxious chemicals. Watch Video! R-Control Perform Guard EPS Insulation - R-Control has created building systems for walls, floors, roofs, and ceilings. Covered with a skin of OSB (oriented strand board) to provide an even, continuous nailing surface, these panels are made of expanded polystyrene, and filled with concrete to provide superior insulation without the settling or looping typical of fiberglass, rock wool, and cellulose-based insulation systems. Watch Video! Air and Vapor Retarders Housewraps help protect against air infiltration, manage moisture vapor, and protect walls when rain and water get behind siding, brick, or stucco. Credit: BobVila.com These are two things that sometimes can do the same job. How to design and install them depends a great deal on the climate and what method of construction is chosen. No matter where you are building, water vapor condensation is a major threat to the structure of a house. In cold climates, pressure differences can drive warm, moist indoor air into exterior walls and attics. It condenses as it cools. The same can be said for very Southern climates, just in reverse. As the humid outdoor air enters the walls to find cooler wall cavities it condenses into liquid water. This is the main reason why some of the old buildings in the South that have been retrofitted with air conditioners now have mold and rotten wood problems. Regardless of your climate, it is important to minimize water vapor migration by using a carefully designed thermal envelope and sound construction practices. Any water vapor that does manage to get into the walls or attics must be allowed to get out again. Some construction methods and climates lend themselves to allowing the vapor to flow towards the outdoors. Others are better suited to letting it flow towards the interior so that the house ventilation system can deal with it. The Airtight Drywall Approach and the Simple CS system are other methods to control air and water vapor movement in a residential building. These systems rely on the nearly airtight installation of sheet materials such as drywall or gypsum board on the interior as the main barrier, and carefully sealed foamboard and/or plywood on the exterior.

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